What is the difference? (2)

[Shinya Maki]

What is the difference in meaning between #1 and #2 below?
1. This is the biggest single issue facing older people.
2. This is the single biggest issue facing older people.

Shinya Maki

[Pete]

What is the difference in meaning between #1 and #2 below?
1. This is the biggest single issue facing older people.
2. This is the single biggest issue facing older people.

Shinya Maki
If these were actually said, I think the meanings would be intended to be the same. In both cases, I'd say that "single" is redundant (since the superlative "biggest" implies uniqueness), used for emphasis of that fact.

The structure of the first sentence possibly allows for a different reading. If you can come up with a meaning of "single issue" (maybe an issue with only one aspect) as compared with a "multiple issue" (maybe a much more complex issue), then you could claim that "biggest single issue" means the biggest issue of that sort. I don't think, however, that there is a reasonable meaning for the phrase "single issue" by itself as a type of issue. Thus I'd say that wherever you put "single", it modifies the idea "biggest issue" in the way I described.